This invention relates to a process for removing hydrogen sulfide from gases, particularly coal distillation gases by first scrubbing the gases with ammoniacal liquor, and then in a fine purification stage, by scrubbing the gases with a caustic soda solution or a caustic potash solution, preferably with a concentration of about 3% to 5% NaOH.
It is known in the art to use an ammonia-containing scrubbing solution for coarse scrubbing of hydrogen sulfide out of gases, and after this coarse scrubbing process, to use a caustic soda solution to carry out a fine purification of the gas. It is also known in the art to directly utilize the spent sulfur-ladden caustic soda solution for separating fixed ammonia compounds when purifying coal distillation gases using the above process.